The present invention relates to catalysts for the oxidative polymerization of fluorophenols and a method for the oxidative polymerization of fluorophenols wherein such catalysts are used. More particularly, this invention relates to catalysts for the oxidative polymerization of fluorophenols useful for the synthesis of engineering plastics, such as fluoropolyarylene ether, with excellent heat resistance and flame resistance, as well as small friction factor, and a method for the oxidative polymerization of fluorophenols wherein such catalysts are used.
Further, the present invention relates to poly(oxyfluorophenylene) compounds. More particularly, the present invention relates to soluble poly(oxyfluorophenylene) compounds with excellent heat resistance, membrane-formability and chemical stability.
Polyarylene ethers are known as engineering plastics having characteristics such as excellent heat resistance, mechanical strength, drug resistance, dimensional stability, electric performance, and workability, and are used in various industrial fields, such as mechanical parts, gas separating membranes, conductive resins, and functional rubbers.
In addition, they are also known as being prepared by the oxidative coupling of for example, 2,6-dimethylphenol, using various copper-amine complex catalyst and oxygen.
More specifically, polyarylene ether, particularly poly (2,6-dimethyl-1,4-arylene)ether is prepared by the oxidative coupling of 2,6-dimethylphenols using a tertiary amine (for example, pyridine, tetramethylene diamine, triethylamine, etc.) and a copper (I) salt (e.g. cuprous chloride) which is capable of forming a complex therewith, as a catalyst. This reaction is a less expensive reaction system, since it uses dissolved oxygen as the oxidizing agent and produces water. However, for phenols (such as 2,6-difluorophenol), which contain an electron withdrawing substituent, due to its high oxidation potential, oxidation by copper complex catalysts is difficult, and reports on polymers obtained by oxidative polymerization are scarce. The only method reported so far on the oxidative polymerization of 2,6-difluorophenol involves the use of oxidase as a catalyst (Ryohei Ikeda, Hozumi Tanaka, Hiroshi Uyama and Shiro Kobayashi, 76th Spring Annual Meeting of Japan Chemical Society) However, the degree of polymerization for the polymer product is extremely low, because enzymatic reactions require the use of water as the solvent, making the method unpractical.
Thus, the objective of the present invention is to provide a novel catalyst useful for the oxidative polymerization of fluorophenols, which does not require the use of water as solvent, and enables the polymerization of fluoropolyarylene ether in high degree, and to provide a novel method of the oxidative polymerization of fluorophenols.
Further, another objective of the present invention is to provide poly(oxyfluorophenylene) compounds which have so far been deemed impossible to synthesize.
In order to overcome the above objectives, the present invention firstly provides, a copper complex catalyst for the oxidative polymerization of fluorophenols that contain at least one hydrogen atom as well as a fluorine atom bonded to the carbon atoms constituting the benzene ring, which has an oxidation potential in the range of xe2x88x921V to 2V.
Further, the invention of the present application secondly provides the above copper complex catalysts for the oxidative polymerization of fluorophenols, wherein the ligand is at least one compound chosen from aliphatic cyclic amines and alkylene cross-linked compounds thereof. The invention thirdly provides a copper complex catalyst for the oxidative polymerization of fluorophenols, wherein the ligand is at least one compound chosen from alkylenediamines and alkylene cross-linked compounds thereof. Fourthly, the present invention provides the copper complex catalysts for the oxidative polymerization of fluorophenols according to any one of claims 1 to 3, wherein the complex is a mononuclear or a binuclear copper complex.
Further, the invention of the present application fifthly provides a method for the oxidative polymerization of fluorophenols that contain at least one hydrogen atom as well as fluorine atoms bonded to the carbon atoms constituting the benzene ring, wherein the copper complex catalyst according to any one of the above-described first to fourth inventions is used. The present invention sixthly provides a method for the oxidative polymerization of fluorophenols represented by the following formula (II): 
(wherein R1, R2, R3 and R4 each represents a hydrogen atom, a hydrocarbon group or a fluorine atom, at least one of R1, R2, R3 and R4 being a fluorine atom), according to the aforesaid fifth invention.
The invention or the present application seventhly provides a poly(oxyfluorophenylene) compound represented by the following formula (I): 
wherein R1, R2, R3 and R4 each represents a hydrogen atom or a fluorine atom, at least one of which is a fluorine atom, and n is an integer larger than or equal to 2, which represents the degree of polymerization.
Furthermore, the invention of the present application eighthly provides the above-described poly(oxyfluorophenylene) compounds prepared by the oxidative polymerization of the fluorophenol represented by the following formula (II): 
wherein R1, R2, R3 and R4 each represent a hydrogen atom or a fluorine atom, at least one of which is a fluorine atom. The invention of the present application ninthly provides a poly(oxyfluorophenylene) compound obtained by the re-polymerization of the oligomers of the seventh or eighth inventions.
The invention of the present application tenthly provides poly(oxyfluoro-1,4-phenylene-cooxy-1,4-arylene) compounds obtained by the oxidative polymerization of the fluorophenols represented by formula (II) of the eighth invention, with substituted phenols.
Further, the present invention eleventhly provides a method for producing poly(oxyphenylene) compounds, wherein the method for the oxidative polymerization of the eighth invention is performed in the presence of a copper complex catalyst selected from the group consisting of a mononuclear copper complex containing an aliphatic cyclic amine-type multidentate ligand, a mononuclear copper complex containing an alkylenediamine ligand and a binuclear copper complex containing either an aliphatic cyclic amine-type multidentate ligand or a binuclear ligand wherein an alkylenediamine ligand is linked by an alkyl chain.
Furthermore, a method to produce poly(oxyfluoro-1,4-phenylene-cooxy-1,4-arylene) by the oxidative polymerization method according to the ninth invention, in the presence of a catalyst selected from the group consisting of a mononuclear copper complex containing an aliphatic cyclic amine-type multidentate ligand, a mononuclear copper complex containing an alkylenediamine ligand and a binuclear copper complex containing either an aliphatic cyclic amine-type multidentate ligand or a binuclear ligand wherein an alkylenediamine ligand is linked by an alkyl chain is provides as the twelfth invention.
Moreover, as the thirteenth invention, a method for producing poly(oxyphenylene) compounds with substituted phenyl ether as a side chain, which comprises reacting any one of the aforesaid poly(oxyphenylene)compounds with a substituted phenol to replace the fluorine group with a substituted phenyl ether group is provided.
The present invention has the features described above. Further embodiments of the present invention are discussed below in detail.
The copper complex catalyst used as a catalyst for the oxidative polymerization of fluorophenols of the present invention is composed of a ligand or a group of ligands, and copper (Cu). The ligand in this case should be chosen so that the oxidation potential of the copper complex is in the range of xe2x88x921V to 2V. It is important that this requirement is fulfilled, and examples of preferable ligands include at least one compound chosen from aliphatic cyclic amines and alkylene cross-linked compounds thereof, as well as at least one compound chosen from alkylenediamines and alkylene cross-linked compounds thereof.
More specifically, preferable examples of the catalysts for the oxidative polymerization of the present invention include compounds selected from mononuclear complexes composed of aliphatic cyclic amine-type multidentate legends, mononuclear complexes composed of alkylenediamine ligands and binuclear complexes with polynuclear ligands wherein such mononuclear complexes are linked via an alkyl chain. Specific examples of such copper complexes are as follows:
 less than A greater than  1,4,7-Triazacycloalkane Copper (II) Type Complexes
 less than B greater than  ((bis-(1,4,7-triazacycloalkyl)alkane)-biscupric(II) halide type complexes
 less than C greater than  ((bis(1,4,7-triazacycloalkyl)alkane)-biscupric(II) perchlorate-type complexes
 less than D greater than  ((bis(1,4,7-triazacycloalkyl)alkane)biscupric(II) perchlorate-type complexes
 less than E greater than  ((bis(1,4,7-triazacycloalkyl)alkane)biscupric(II) hexafluorophosphate-type complexes
 less than F greater than  ((bis(1,4,7-triazacycloalkyl)alkane)biscupric(II) tetrafluoroborate-type complexes
 less than G greater than  ethylenediamine cupric(II)-type complexes
 less than H greater than  propanediamine cupric(II)-type complexes
 less than I greater than  cyclohexanediamine cupric(II)-type complexes
 less than J greater than  ((N,Nxe2x80x2bis(aminoalkyl)-alkylenediamine) biscupric(II) chloride- type complexes
 less than K greater than  ((N,Nxe2x80x2-bis(aminoalkyl)alkylenediamine) biscupric(II) bromide-type complexes
 less than L greater than  ((N,Nxe2x80x2-bis(aminoalkyl)-alkylenediamine) biscupric(II) perchlorate-type complexes
 less than M greater than  ((N,Nxe2x80x2-bis(aminoalkyl)alkylenediamine) biscupric(II) trifluoromethanesulfonate-type complexes
 less than N greater than  ((N,Nxe2x80x2-bis(aminoalkyl)-alkylenediamine) biscupric(II) hexafluorophosphate-type complexes
 less than O greater than  ((N,Nxe2x80x2-bis(aminoalkyl)-alkylenediamine) biscupric(II) tetrafluoroborate-type complexes
By using, for example, the above-described copper complexes, a high degree of polymerization is enabled for the oxidative polymerization of fluorophenols of the present invention.
The fluorophenol such as that represented by the above formula (II), which is involved in the method of the present invention, are phenols with at least one fluorine atom and at least one hydrogen atom bonded to the carbon atom constituting the benzene ring, wherein such benzene rings may contain substituents such as hydrocarbon groups, which may contain one or more substituents, and electron withdrawing substituents other than fluorine atom (e.g. chloro group, bromo group, iodo group, nitro group, cyano group, etc.).
Among such fluorophenols, the fluorophenols of the above formula containing a hydrogen atom at the 4-position of the benzene ring are representative examples for the present invention. Some specific examples are 2-fluorophenol, 3-fluorophenol, 2,6-difluorophenol, 2,5-difluorophenol, 2,3-difluorophenol, 3,5-difluorophenol, 2,3,5-trifluorophenol, 2,3,6-trifluorophenol, 2,3,5,6-tetrafluorophenol, etc.
The catalyst of the present invention is characteristic in that the valence change of the central metallic copper from univalent to trivalent is responsible for the catalytic activity and the ligand contributes to the regulation of the oxidation-reduction potential and the rapid formation of the oxygen cross-linking coordination. These copper complexes are not only useful as catalysts for the oxidative polymerization of fluorophenols but are also useful as catalysts for the oxidative polymerization of phenols with other electron withdrawing substituents (e.g. chloro group, bromo group, iodo group, nitro group, cyano group, etc.).
The oxidative polymerization of the present invention may preferably be carried out at a temperature from around ordinary temperature to about 70xc2x0 C. under oxygen in the presence of a solvent. Examples of solvents which may preferably be used are benzene, toluene, o-xylene, m-xylene, monochlorobenzene, o-dichlorobenzene, m-dichlorobenzene, nitrobenzene, as well as halogenated hydrocarbons such as dichloromethane, 1,2-dichloropropane, 1,1,2,2-tetrachloropropane, etc. These solvents may be used alone or as a mixture of two or more of preferable solvents. Further, the reaction is accelerated by the use of base as a promoter. Examples of such base usable as promoters are sodium hydroxide, potassium hydroxide, trimethylamine, N,Nxe2x80x2-dimethylalkylamine, N-methyl-pyrrolidine, 2,6-diphenylpyridine, etc.
According to the invention of the present application, a poly(oxyfluorophenylene) compound of the general formula (I), wherein R1, R2, R3 and R4 are hydrogen atoms or fluorine atoms, at least one of which is a fluorine atom, and n is an integer greater than or equal to 2, is provided. In this case, as long as n is greater than or equal to 2, the product may be an oligomer of comparatively low molecular weight with a degree of polymerization (n) less than 20, or a polymer with a degree of polymerization (n) greater than or equal to 20.
Further, the poly(oxyfluorophenylene) compounds of the present invention may be those prepared by re-polymerizing the oligomer obtained by the oxidative polymerization of fluorophenols. In this case, conditions for the re-polymerization are not particularly limited, nor are the catalysts, solvents, polymerization temperature and reaction time.
Furthermore, the present invention provides poly(oxyfluoro-1,4-phenylene-co-oxy-1,4-arylene) compounds prepared by the copolymerization of the above fluorophenols with substituted phenols. Various substituted phenols may be used, examples of which include 2-methylphenol, 3-chlorophenol, 2,5-dimethylphenol, 3,6-diphenylphenol, 2,6-dicyclohexylphenol, 2,5-dichlorophenol, 3,6-dibromophenol, 2,3,5-triethylphenol, 2,3,5,6-tetramethylphenol, etc.
Moreover, the present invention provides a method for preparing poly(oxyfluorophenylene) compounds with substituted phenyl ether groups on its side chain, by reacting the poly(oxyfluorophenylene) compound described above with a substituted phenol to replace the fluoro group with a substituted ether group, Such method of production may be exemplified by the following scheme (III): 
Thus in the above scheme (III), poly(oxyfluorophenylene) compound of formula (I), wherein R2 and R4 are fluorine, is used as a starting material and reacted with a phenol containing the substituent R.
The poly(oxyfluorophenylene) compound of the starting material is not limited to that shown in scheme (III), and may contain 1 to 4 fluorine atoms, whose positions are not limited to 2,6. Various compounds such as poly(2-monofluoro-1,4-phenylne oxide), poly(3-monofluoro-1,4-phenylene oxide), poly(2,5-difluoro-1,4-phenylene oxide) poly(3,5-difluoro-1,4-phenylene oxide), poly(2,3,5-trifluoro-1,4-phenyleneoxide), poly(2,3,6-trifluoro-1,4-phenylene oxide), poly (2,3,5,6-tetrafluoro-1,4-phenylene oxide), etc. may be used as the starting material.
Further, the substituted phenol to be reacted may contain the substituent (R) at the ortho, meta or para positions, and may contain the same or different substituents at any two or more positions among the 2- to 6- positions in relation to the OH group, such as 2,4-, 2,5-, 3,5- etc. The substituent R may be chosen from various substituents such as substituents containing halogen atom, O, S or N, alkyl groups and substituted alkyl groups. Examples of such substituted phenols are p-phenolsulfonic acid, o-nitrophenol, m-chlorophenol, etc.
Of course, in the present method for producing poly(oxyphenylene) compounds with substituted phenyl ether group in its side chain, the poly(oxyfluorophenylene) compounds and the substituted phenol used as the starting material are not limited to those exemplified above, and phenyl ether groups containing various substituents may be introduced thereto. By introducing such various phenyl ether groups, the mechanical and physical properties of the poly(oxyphenylene) compounds obtained may be controlled.
In scheme (III), the phenyl other is, in other words, introduced into the compound by the substitution of the fluorine atom of the starting poly(oxyfluorophenylene) compounds (chemical formula (I)) with a substituted phenol. Conditions of such reactions are not limited in particular, whereby catalysts, solvents, reaction temperatures and reaction time may be selected depending upon the substituted phenol to be introduced or the poly(oxyfluorophenylene) compound used as the starting material.
Examples are shown bellow to further illustrate the present invention in detail. It is needless to say, that the scope of the present invention is not to be limited by the following examples.